I am running Eclipse 4.3.0 with JasperReports Studio 5.0.3.
When I try to add a data adapter and test the connection I get a null pointer exception if I don't have a Java project in my workspace.
Testing the connection works as soon as I create an empty java project.
I think this is because a class loader is only found in AbstractDataAdapterWizard.java if a java project exists in the workspace.
See code starting at line 136 and in particular the iteration over the projects at line 151 in widgetSelected(SelectionEvent e).